Perovskite oxyhydrides have attracted recent attention due to their intriguing properties such as ionic conductivity and catalysis, but their repertoire is still restricted compared to perovskite oxynitrides and oxyfluorides. Historically, perovskite oxyhydrides have been prepared mostly by topochemical reactions and high-pressure (HP) reactions, while in this study, we employed a mechanochemical (MC) approach, which enables the synthesis of a series of ABO₂H-type oxyhydrides, including those with the tolerance factor (t) much smaller than 1 (e.g., SrScO₂H with t = 0.936) which cannot be obtained by HP synthesis. The octahedral tilting, often present in perovskite oxides, does not occur, suggesting that the lack of π-symmetry of the H 1s orbital and the large polarization destabilize tilted low-symmetry structures. Interestingly, SrCrO₂H (t = 0.997), previously reported with the HP method, was not achieved with the MC method. A comparative analysis revealed a correlation between the feasibility of MC reactions and the (calculated) shear modulus of the starting reagents (binary oxides and hydrides). Notably, this indicator is not exclusive to oxyhydride perovskites but extends to oxide perovskites (SrMO₃). This study demonstrates that MC synthesis offers unique opportunities not only to expand the compositional space in oxyhydrides in various structural types but also to provide a guide for the choice of starting materials for the synthesis of other compounds.

中文翻译：

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钙钛矿氢氧化物的机械化学合成：剪切模量的见解

钙钛矿氢氧化物由于其离子导电性和催化作用等有趣的特性而引起了人们的关注，但与钙钛矿氮氧化物和氟氧化物相比，它们的性能仍然受到限制。历史上，钙钛矿氢氧化物主要通过拓扑化学反应和高压（HP）反应来制备，而在本研究中，我们采用了机械化学（MC）方法，可以合成一系列AB O ₂ H型氢氧化物，包括那些容差因子( t )远小于1的材料(例如，t =0.936的SrScO ₂ H )，其不能通过HP合成获得。钙钛矿氧化物中经常存在的八面体倾斜并未发生，这表明 H 1s 轨道缺乏 π 对称性和大极化使倾斜的低对称性结构不稳定。有趣的是，之前用 HP 方法报道的 SrCrO ₂ H ( t = 0.997) 并未用 MC 方法实现。比较分析揭示了 MC 反应的可行性与起始试剂（二元氧化物和氢化物）的（计算的）剪切模量之间的相关性。值得注意的是，该指标不仅适用于氢氧钙钛矿，还适用于氧化物钙钛矿（Sr M O ₃）。这项研究表明，MC 合成不仅提供了独特的机会来扩展各种结构类型的氢氧化物的组成空间，而且还为其他化合物合成的起始材料的选择提供了指导。